Are English teachers income tax exempt in Japan for the first 2 years? In Korea they are.

Americans are tax exempt for two years if working full time at a school or tertiary institution under MEXT. Dispatch doesnt count: you must be on the school or university payroll. Some US states still levy state taxes, regardless of federal status.

Exempt from which country's taxes, ETA? G Cthulhu referred to Japanese taxes. Americans still have to file for taxes from money earned abroad, but they are exempt from paying U.S. taxes on money under a certain amount (roughly $92,000).

Also, what is your nationality? If you meant your own country's taxes, it would help to know that.

As for taxes paid in the US, there is no time limit to US tax exemption if, as Glenski says, you earn under a certain amount indefinitely. But again, you must still file US taxes. There are other countries with this reciprocity arrangement such as Canada. Note you are still getting zinged on each paycheck for taxes paid to the Japanese government. Whatever company you work for, should be paying your taxes for you each month, and at the end of the year should give you back a small overpayment on your December paycheck.

MEXT is the governmental office in charge of several things, including education. It is not a program. It makes national policies and guidelines for schools, among other things.
http://www.mext.go.jp/english/

As for taxes paid in the US, there is no time limit to US tax exemption if, as Glenski says, you earn under a certain amount indefinitely. But again, you must still file US taxes. There are other countries with this reciprocity arrangement such as Canada. Note you are still getting zinged on each paycheck for taxes paid to the Japanese government. Whatever company you work for, should be paying your taxes for you each month, and at the end of the year should give you back a small overpayment on your December paycheck.

All sorts of wrong in that post.

Americans are not tax exempt. They get an automatic deduction on earnings, as glenski mentioned. It's not the same thing. It's not a reciprocal arrangement with anyone: the US IRS rules simply say that all Americans get a deduction on overseas earned income. If you're American and fit the bill for coverage by the tax treaty between the US and Japan then you *do not* pay Japanese tax for the first two years in Japan: you're liable only for US tax, but few people make enough to trigger the liability.